Asbestos Sampling: Why is it Done?

Asbestos is a term describing a set of six naturally occurring minerals. Asbestos minerals have many great uses when milled, including resistance to heat, fire and caustic materials, tensile strength, soundproofing and insulation. Asbestos has been used for thousands of years, sometimes called the “Miracle Mineral”. Because of its versatility, asbestos was used in many industries including construction, manufacturing, shipping, and has been identified in retail products as well. Unfortunately, asbestos has been linked to adverse health effects such as asbestosis (scarring of the lung tissue), lung cancer, mesothelioma, and colon cancer.

Regulatory Agencies such as the United States Environmental Protection Agency (EPA), the Occupational Safety and Health Administration (OSHA) and State and Local agencies have implemented rules and regulations to identify and allow people to work safely with asbestos containing materials (ACMs). The EPA defines an ACM as any material that contains greater than 1% asbestos. There are thousands of suspect asbestos-containing building materials and products. Suspect materials must be treated as an ACM until they are sampled and analyzed at an approved laboratory using prescribed methodologies. Only laboratory analysis can indicate that a material contains no detectible asbestos. Only then may a previously identified suspect material be treated as a non-asbestos containing material.

Asbestos Surveys

To collect a valid bulk sample to be analyzed for asbestos content, the person collecting the sample must have a current EPA Building Inspector certificate. Other state certifications and licensing requirements may be applicable.

Pre-Demolition Survey – Prior to the demolition of a building or structure, all suspect materials must be sampled. ACMs or suspect ACMs must be properly removed prior to the demolition.

Pre-Renovation Survey – Prior to renovation in or on a building or structure, all suspect materials that may be impacted during the renovation must be sampled to prevent disturbance and potential exposure to workers or the general public.

OSHA Compliance Survey – Employers are required to conduct a survey of their buildings and structures to identify any suspect materials employees may come in contact with. There are many additional requirements employers must follow for ACMs and suspect ACMs.

Directed Bulk Sampling – When there is a disturbance or an unknown material is identified, a building owner may direct a building inspector to collect samples of specific materials.

Asbestos Sampling

How many samples need to be collected? The EPA’s Asbestos Hazard Emergency Response Act (AHERA) defines how many samples to collect for each homogenous material depending on its classification. Materials are classified as either thermal system insulation (TSI), surfacing materials or miscellaneous.

Sampling requirements for each classification:

TSI – Asbestos-containing material applied to pipes, fittings, boilers, breeching, tanks, ducts, or other interior structural components to prevent heat loss or gain or water condensation. For each homogeneous material associated with a system three samples are required.

Surfacing Materials – ACM that has been sprayed or troweled on surfaces (walls, ceilings or structural members) for acoustical, decorative, fireproofing or other purposes. Nine samples are suggested for each homogeneous material. However, there is what is known as the 3-5-7 rule which is the AHERA minimum requirement. It is based on square footage of the suspect material present. For between one and 1,000 square feet of material minimum of three samples are collected, quantities between 1,001-5,000 square feet a minimum of five samples are collected, and for material greater than 5,000 square feet, a minimum of seven samples are required to be collected.

Miscellaneous Materials – For other largely non-friable products such as floor tiles, mastics, roofing materials and sidings, a minimum of two samples are collected.

Why are there a minimum of two samples collected? If the first sample is negative for asbestos content, the second sample is used as negative confirmation.

Not all samples are analyzed. A positive stop may be used. For example, if a set of seven samples of spray-on insulation is submitted to the lab and the first sample comes back with 20% chrysotile, the lab will not analyze the remainder of the set because the material is now identified as an ACM.

The goal of a survey is not to “find asbestos”, as we are already treating suspect materials as an ACM. The goal of sampling and analysis is to identify material that does not contain asbestos so it may be treated as a non-asbestos containing material.